I managed to unlock The Lost character in The Binding of Isaac: Rebirth earlier this week. The Lost is the super challenge mode character in the game. He starts with flying and can make any deals with the devil for free... But any damage kills him. Period. You can't get extra health or pick up soul hearts or anything like that. Take damage and die. There are ways to either make yourself invincible or to bring yourself back to life that still work with The Lost but they are few and far between.
One of the streamers I watch who plays the game did a day of playing The Lost. He focuses more on entertainment than on speed running (though he does some of that too) so the way he played was he used a memory editor to hack it so the first item he picked up was guaranteed to be a holy mantle from the treasure room or a dead cat from the curse room. This way he would get one of the two key survival items without having to reset hundreds of times to get a viable run. (Holy mantle makes it so the first hit you take in any room is prevented. Dead cat gives you 9 extra lives.)
The main Issac speedrunner I watch talked a bit about how to get better at the game. His main advice was to play as The Lost without scumming for a holy mantle or a dead cat. The theory there was you'd have to learn how to deal with every room without taking any damage and that was bound to make you better at playing the game when you went back to playing a normal character.
I'm working on achievements so there's no way I'd hack the game to give me specific items. I think it makes a lot of sense as a convenience matter for entertainment purposes but I also think it's cheating. On the other hand the idea of starting just any item seems insane. I find myself getting hit by early game spiders way too often if I don't have a damage boost. Maybe there is something to be said for forcing myself to do it to get better, but it really isn't much fun. But then there's the fact that I've died 150 times since I unlocked The Lost and reset probably 5 times per death and have only seen one holy mantle! So scumming for those two items specifically would take forever and that isn't much fun either.
So what I'm doing is resetting until I get an item that either makes me immediately better or has real long term potential. So things like a blank card or a crystal ball or a damage boost. Mediocre or useless items prompt a reset. If I don't get a really good item from the treasure room I'll gladly hop into the curse room, which is almost guaranteed to be death. Unless I get a dead cat, guppy's collar, or a telepill I will die.
I have actually managed to complete one run out of the 700ish tries. It opened on a dead cat and led to extra damage boosts from almost every boss. This is pretty unlikely since a lot of the boss items are only health ups, but my first two bosses dropped a halo and a magic mushroom. By the end of the run I had scythes, and double shot, and was guppy. I got to Isaac on one previous run and killing him without ever taking damage seemed beyond my abilities, but this time I had enough guppy flies that he immediately transitioned to phase 3 upon my entering the room. Huzzah!
Am I actually getting better at the game or did I just hit the lottery of good items? Probably a combination of the two. But it does mean there's some hope for getting the rest of the achievements done given enough time... Actually, getting lucky with items probably isn't good enough for the boss rush... And if it is, should I be playing on hard mode? I need to beat the boss rush with The Lost on hard mode at some point too...
Maybe what I should do next is hard mode with some normal characters to get a feel for it and then go back to The Lost.